Make max chars in cell error message more helpful

csv-validator-core/src/main/scala/uk/gov/nationalarchives/csv/validator/MetaDataValidator.scala

@@ -355,15 +355,23 @@ class RowIterator(parser: CsvParser, progress: Option[ProgressFor], maxCharsPerC
 
   private var index = 1
   private var current = toRow(Try(parser.parseNext()))
+  private var potentialHeaderRow: Option[Row] = None
 
   @throws(classOf[IOException])
   override def next(): Row = {
     val row = current match {
-      case Success(row) => row
+      case Success(row) =>
+        if(index == 1 && potentialHeaderRow.isEmpty) potentialHeaderRow = Some(row) // this is here in case the old API is used that doesn't call 'skipHeader'
+        row
       case Failure(ex: TextParsingException) if(ex.toString.contains("exceeds the maximum number of characters")) =>
+        val cellLocationMsg =
+          potentialHeaderRow match {
+            case Some(headerRow) => s"in the cell located at line: ${ex.getLineIndex}, column: ${headerRow.cells(ex.getColumnIndex).value},"
+            case None => s"in column ${ex.getColumnIndex + 1} of the header row"
+          }
+
         val customMessage =
-          s"The number of characters in the cell located at line: ${ex.getLineIndex + 1}, column: ${ex.getColumnIndex + 1}, " +
-            s"is larger than the maximum number of characters allowed in a cell ($maxCharsPerCell); increase this limit and re-run."
+          s"The number of characters $cellLocationMsg is larger than the maximum number of characters allowed in a cell ($maxCharsPerCell); increase this limit and re-run."
         throw new Exception(customMessage)
       case Failure(ex) => throw ex
     }
@@ -385,7 +393,9 @@ class RowIterator(parser: CsvParser, progress: Option[ProgressFor], maxCharsPerC
   @throws(classOf[IOException])
   def skipHeader(): Row = {
     this.index = index - 1
-    next()
+    val row = next()
+    this.potentialHeaderRow = Some(row)
+    row
   }
 
   override def hasNext: Boolean = current match {

csv-validator-core/src/test/resources/uk/gov/nationalarchives/csv/validator/api/metaDataWithALongCellLength.csv

@@ -0,0 +1,2 @@
+col1,col2
+row1Col1,row1Col2LongCellLength

csv-validator-core/src/test/scala/uk/gov/nationalarchives/csv/validator/api/CsvValidatorMaxCharsPerCellSpec.scala

@@ -25,11 +25,19 @@ class CsvValidatorMaxCharsPerCellSpec extends Specification with TestResources {
     def app(maxChars: Int=4096) = new CsvValidator with AllErrorsMetaDataValidator { val pathSubstitutions: List[(String, String)] = List[(String,String)](); val enforceCaseSensitivePathChecks = false; val trace = false; val skipFileChecks = false; val maxCharsPerCell: Int = maxChars }
     def parse(filePath: String, maxChars: Int=4096): Schema = app(maxChars).parseSchema(TextFile(Paths.get(filePath))) fold (f => throw new IllegalArgumentException(f.toString()), s => s)
 
-    "fail if the number of characters in a cell is more than the maxCharsPerCell number" in {
+    "fail if the number of characters in a cell in the header is more than the maxCharsPerCell number and indicate the column number" in {
       val maxCharsAllowed = 2
       val validatedNel = app(maxCharsAllowed).validate(TextFile(Paths.get(baseResourcePkgPath).resolve("metaData.csv")), parse(baseResourcePkgPath + "/schema.csvs", maxCharsAllowed), None).swap
       validatedNel.toList.head.toList must beEqualTo(
-        List(FailMessage(ValidationError,"java.lang.Exception: The number of characters in the cell located at line: 1, column: 1, is larger than the maximum number of characters allowed in a cell (2); increase this limit and re-run.",None,None))
+        List(FailMessage(ValidationError,"java.lang.Exception: The number of characters in column 1 of the header row is larger than the maximum number of characters allowed in a cell (2); increase this limit and re-run.",None,None))
+      )
+    }
+
+    "fail if the number of characters in a cell in a non-header row is more than the maxCharsPerCell number and indicate the column name" in {
+      val maxCharsAllowed = 15
+      val validatedNel = app(maxCharsAllowed).validate(TextFile(Paths.get(baseResourcePkgPath).resolve("metaDataWithALongCellLength.csv")), parse(baseResourcePkgPath + "/schema.csvs"), None).swap
+      validatedNel.toList.head.toList must beEqualTo(
+        List(FailMessage(ValidationError,"java.lang.Exception: The number of characters in the cell located at line: 1, column: col2, is larger than the maximum number of characters allowed in a cell (15); increase this limit and re-run.",None,None))
       )
     }